Instrument for linear measurements.



No. 806,971. IPATENTED DEC. 12, 1905.

- G. GOSSA.

INSTRUMENT FOR LINEAR MEASUREMENTS.

APPLICATION FILED MAYZS, 1905 UNITED STATES PATENT oEEIoE.

GEoRG GossA,-oE BRESLAU, GERMANY, AssIGNoR or ONE-THIRD TO ERwrN HEYBER, or POST STROPPEN, GERMANY, AND ONE-THIRD TO MAX GossA, or BREsLAU, GERMANY.

INSTRUMENT FOR LINEAR MEASUREMENTS.

Specification of Letters Patent.

Patented Dec. 12, 1905.

Application filed May 26, 1905. Serial No. 262,458i

To all whom) it may concern.-

Be it known that I, GEoRG GrossA, a subject of the King of Prussia, German Emperor, residing at Breslau, Germany, have invented certain new and useful Improvements in Instruments for Linear Measurements, of which the following is a specification.

- This invention relates to improvements in instruments for linear measurement. For obtaining exact results the length of the base used in instruments for measuring distances must, as is known, be as great as possible. ment in a horizontal plane becomes inconvenient, since if a long cord or the like is used two persons situated at a distance apart are required to efiect the measurement and if a rigid base is used instead of a flexible one a considerable amount of lateral space, which is not always available, is required. For these reasons it has been found desirable to .use a long rigid base arranged in a vertical plane, the triangle determined by the base and the objective being of course also in a vertical plane. This allows of using the instrument in narrow spaces between houses or' angle the known arrangement of a right-angularreflecting-prism, rotatable within wide limits and adapted to indicate the angle by the amount of rotation it requires. This arrangement was rendered impracticable by the fact that with a long base the rays reflected by the prism would no longer reach the fixed telescope when the prism had been rotated through a certain angle and the instrument would only be available for measuring comparatively short distances.

The improved instrument to which the present invention relates is based on the known system of Stubendorf and comprises a rotatable prism arranged at the upper end of a With a long base, however, measurerotatable base and an additional telescope or other suitable sighting instrument, which is arranged at the lower part of the instrument. The said telescope or sighting instrument is directed onto the said rotatable prism and is adapted to be rotated with the latter, so that the relative positions of the two parts do not change. For this purpose the prism is fixed to a rotatable arm, which also carries the tele* scope or sighting instrument.

One form of the invention is diagrammatically illustrated in the annexed drawing.

The rod a, forming the base, is pivotally connected at c to the stake I), so that it can be rotated in a vertical plane. 6 is a telescope fixed to the said rod with its axis perpendicular to the latter. The arm g, carrying the prism f, is pivotally connected to the rod a at 71. To the lower part of the said arm is connected an additional telescope d, directed toward the prism. The fulcrum hof the arm g coincides with the center of the hypotenuse of the prism triangle and the optical axis of the telescope t' is parallel with the side k Zof the said triangle.

When the stake has been driven into the ground, the rod a is rotated until the telescope e is directed on the object cl, the distance of which is to be measured. Then the arm 9 is rotated until the image reflected by the prism falls into the telescope z. The angle contained by the rod a and arm g is then equal to the angle at cl. This angle can be directly read off the scale 02 below the arm 9 by means of a Vernier or the like and forms the second factor required for determining the triangle m d h, the length of the base a being known.

The instrument described is more particularly designed for military purposes.

What I claim as my invention, and desire to secure by Letters Patent of the United States,

1. In an instrument for linear measurement the combination of a rotatable base, a sighting the combination of a rotatable base, a sighting instrument carried thereby, a rotatable arm pivoted to said base, a reflecting-prism carried by said arm, and a sighting instrument also carried by said arm and directed toward said prism substantially as described.

3. In an instrument for linear measurement the combination of a rotatable base, a sighting instrument carried thereby, a rotatable arm pivoted to said base, a reflecting-prism carried by said arm, a sighting instrument also carried by said arm and directed toward said prism and means for indicating the angle contained by the aforesaid base and arm substantially as described.

t. In an instrument for linear measurement the combination of a rotatable base, a sighting instrument carried thereby a rotatable arm pivoted to the upper end of said base, a rightangular reflecting-prism carried by said arm and a sighting instrument also carried by said arm and directed toward the prism substantially as described.

5. In an instrument for linear measurement the combination of a rotatable base, a sighting instrument carried thereby at right angles thereto, a rotatable arm pivoted to the upper end of said base, a right-angular reflectingprism carried by said arm at its upper end, a sighting instrument also carried by-said arm at the lower end thereof and directed toward said prism and means for indicating the angle contained by said base and arm substantially as described.

6. In an instrument for linear measurement the combination of a rotatable base, a sighting instrument carried thereby, a rotatable arm pivoted to the upper end of said base, a rightangular reflecting-prism carried by said arm at its upper end and having the center of its hypotenuse coinciding with the pivotal point of said arm, a sighting instrument also carried by said. arm at the lower end thereof and directed toward said prism and means for indicating the angle contained by said base and arm substantially as described.

In witness whereof I have signed this specification in the presence of two witnesses.

GEORG GOSSA.

Witnesses:

Dr. PErPBYLToK, ERNST KA'rz. 

